Field of the Invention
This invention relates to a diacyl peroxide composition comprising a particular diacyl peroxide mixture which is dissolved in a solvent in a particular ratio, and particularly to a diacyl peroxide composition which is less degradable on storage under cooling to facilitate a long term storage and which is excellent in processability and workability.
Heretofore, dibenzoyl peroxide (hereinafter referred to as BPO), which is a member of the class of diacyl peroxides, has been widely used as a polymerization initiator for vinyl monomers, a curing agent of unsaturated polyester resins and also a cross-linking agent for silicone rubbers and the like.
However, there are drawbacks in that BPO which is in a pure state or a wet state, has little solubility in the monomer, solvent or unsaturated polyester resin, and in addition, a poor dissolving ability due to the solid nature thereof so that it takes a long time to dissolve the same.
Moreover, there is a danger in that pure BPO may sensitively respond to a friction or impact to cause an explosive decomposition.
In order to ameliorate these drawbacks, BPO has been incorporated in various physical forms, for example it is dispersed in a plasticizer which is solid at room temperature, or is dispersed in a liquid plasticizer to give a paste state.
However, there are problems in that the time needed for dissolving it in a monomer or unsaturated polyester resin can be hardly shortened because those of the powder or paste state show a poor workability for measuring the quantity thereof or dissolving them.
There is disclosed in Japanese patent publication NO. 8 905/1965 a liquid curing agent in which a plasticizer is added into di-o-toluoyl peroxide (hereinafter referred to as OTPO) or di-m-toluoyl peroxide (hereinafter referred to as MTPO) for solving this problem.
For this liquid curing agent the dissolving process is not required and the amount measurement as well as the admixing are easily carried out.
This liquid curing agent is also excellent for pump transportation. However, there is still a further problem in this liquid curing agent. It has been known that storage under cooling is usually necessary for peroxides such as BPO in a dissolved state in order to store them without storage degradation for a long term.
Nevertheless, it is preferable to store this liquid curing agent at 14.degree..about.30.degree. C. because there is a problem, when it is stored below 5.degree. C., in that a deposition of solid components or a phase-separation occurrs.